Electronic chips heal after laser blasts

A new self-healing integrated chip could recover in microseconds from problems ranging from low battery power to total transistor failure.

Engineers at California Institute of Technology demonstrated this self-healing capability in tiny power amplifiers. They destroyed parts of the amplifiers’ chips by zapping them multiple times with a high-power laser, then saw the chips develop work-arounds in under a second.

“It was incredible the first time the system kicked in and healed itself. It felt like we were witnessing the next step in the evolution of integrated circuits,” said Ali Hajimiri, the Thomas G. Myers Professor of Electrical Engineering at Caltech. “We had literally just blasted half the amplifier and vaporized many of its components, such as transistors, and it was able to recover to nearly its ideal performance.”

A single fault could render an IC completely useless. The engineers, members of the High-Speed Integrated Circuits laboratory in Caltech’s Division of Engineering and Applied Science, wanted to give such chips a healing ability akin to that of our own immune system – capable of detecting and quickly responding to a number of possible assaults to keep the larger system working optimally.

The devised power amplifier employs many robust on-chip sensors that monitor temperature, current, voltage and power. The information from the sensors feeds into a custom-made application-specific integrated circuit unit on the same chip; this central processor analyzes the amplifier’s overall performance and determines adjustments to system actuators.

“You tell the chip the results you want and let it figure out how to produce those results,” said Steven Bowers, a graduate student in Hajimiri’s lab and lead author of the paper. “The challenge is that there are more than 100,000 transistors on each chip. We don’t know all of the different things that might go wrong, and we don’t need to. We have designed the system in a general enough way that it finds the optimum state for all of the actuators in any situation without external intervention.”

Looking at 20 different chips, they discovered that the amplifiers with the self-healing capability consumed about half as much power as those without, and their overall performance was much more predictable and reproducible.

The capability was first demonstrated in a millimeter-wave power amplifier. Such high-frequency ICs are at the cutting edge of research and are useful for next-generation communications, imaging, sensing and radar applications. By showing that the self-healing technique works well in such an advanced system, the researchers hope to show that the approach can be extended to virtually any other electronic system.